Simulation And Research About HF Broadband High Speed Data Transmission

With the rapid development of HF communication technology in the past 100 years,the rich scientific research results have been achieved.And with the high-speed innovation of electronic communication technology,it has also continuously taken in new ideas,making the HF communication transmission system more high-speed and broadband.Decades ago,the U.S.military began to introduce the HF data transmission system modulation and demodulation series standard MIL-STD-188-110 series.Once launched,it has received wide attention from practitioners.In addition,it has been an important reference system for many HF communication researchers.Firstly,a series of wide band high frequency(WBHF)radio waveforms in the MIL-STD188-110D standard issued by the US Department of Defense in 2017 are studied and compared with the previous versions of 110A,110B and 110C.Secondly,the data frame structure of 110D standard is studied,including synchronous preamble,training sequence,sequence scrambling,interleaving and so on.This thesis’focuses on the algorithms of demodulation,decoding,channel estimation and equalization,including Log-Map,Max-Log-Map and decision boundary,Viterbi,SOVA and BCJR decoding algorithms are also analyzed.The key techniques of channel estimation,timedomain equalization and frequency-domain equalization are also studied.Since the accuracy of channel estimation has a great influence on the performance of high-order modulated waveforms,a channel tracking scheme based on autocorrelation and RLS channel estimation algorithms is proposed in this thesis,the result of channel estimation is more appropriate to the variation of the actual channel,and the system performance of the high-order modulation waveform is guaranteed.In addition,due to the effect of the channel and the equalizer,the amplitude of the equalizer output changes when calculating the soft information of the QAM modulation,which leads to the problem of inaccurate calculation of the soft information.The amplitude gain caused by channel and equalizer is calculated by the equalization process,and the QAM soft demodulation algorithm is improved.Finally,several typical waveforms in 110D are selected for simulation analysis.The performance simulation results of AWGN channel and "Poor" channel with different key technologies are given.The results meet the requirements of the US military standard.